It is conventional on golfing greens and fairways to aerate the grass or turf and this is extremely important because aeration relieves soil compaction, it provides a method to improve the soil mixture around the highest part of a green's roots, and it reduces or prevents the accumulation of excess thatch. In this regard it will be appreciated grass, in order to stay healthy, must have deep healthy roots which demand oxygen and the oxygen supply comes from tiny pockets of air trapped between soil and sand particles. It is necessary to maintain those tiny pockets of air because over a period of time compaction of the soil due to golfer's feet and turf rollers will cause compaction of the soil which is undesirable. That is why constant aeration or the formation of holes in the grass surface is essential.
Conventional spiker rollers include manually propelled rollers having tapped or screw threaded holes into which spikes are inserted and retained therein by a nylock nut. Such spiker rollers are marketed under SAREL spiker rollers and available at www.gardeningtools-direct.co.uk. However one of the major problems with conventional spiker rollers is that upon turning or undergoing a pivotal motion they tend to tear or damage the turf. Another problem is that the steel spikes become separated from their mating tapped or screw threaded holes or sockets in the roller and thus are deposited onto the grass surface where they may become entangled with cutting heads or reels of lawn mowers.
Conventional spiker rollers are also described in U.S. Pat. No. 5,975,441 which refers to a spiker roller assembly having a mounting shaft and a plurality of transversely fixed mounting collars on which spike member quadrants may be attached. This may occur by the mounting collars having a threaded opening to accommodate a respective spiked quadrant. In this arrangement each spike is integral with an individual quadrant.
GB 605974 describes a spiker roller assembly which includes a plurality of discs each furnished with a multiplicity of spikes which are rotatably mounted on a hub of a shaft secured in opposed side members. There is also provided rollers which have T shaped ends and which are driven simultaneously with the discs by a sprocket drive.
GB 127808 describes a spiker roller having discs rotatably mounted on a shaft wherein each disc has in their inner end surfaces recesses for retaining flat bars whose outer ends form spikes extending outwardly from the spiker roller. Teeth on the inner ends of the bars engage with ribs or teeth on the bars. The discs are held together by a rod and the discs are locked to the shaft. The amount of projection of the spikes is varied by withdrawing a spring biased pin and rotating the discs about the shaft after which the pin is engaged with the teeth.
U.S. Pat. No. 1,965,510 refers to a spiker roller having spike mountings each in the form of a sleeve having a boss for detachably retaining an adjacent spike. The spike mountings are pivotally supported on an adjacent rod and can be readily replaced when required. Upon the travel of the roller the pivotal movement of the spikes enables them to be readily extracted from the ground upon continued movement of the roller.
US Patent Publication 2006/0180324 refers to a plurality of spike wheels attached to a harrow wherein each wheel has a plurality of spikes that project outwardly from a cylindrical hub having a pair of opposite ends. Projections at one end of the hub are matingly received within notches in the opposite end of the hub of the next adjacent wheel so that the wheels are interlocked for rotation in unison.
In summary of the patent references described above it will be appreciated that each of the spiker rollers or wheels are extremely complex in structure and thus would be extremely expensive to manufacture. It also seems that they would be ineffective in operation in preventing tearing or damage to the ground upon pivotal movement.